Influence of Co content on the structure and magnetic permeability of nanocrystalline (Fe1-xCox)73.5Cu1Nb3Si13.5B9 alloys

Structural and soft magnetic response of nanocrystalline (Fe1-xCox)(73.5)Cu1Nb3Si13.5B9 (x=0, 0.25, 0.5, 0.75) alloys were investigated. Influences of heat treatment and Co content on the crystallization were analyzed through estimation of the crystalline volume fraction V-cr and thickness of the intergranular amorphous layer A from XRD patterns. High-temperature soft magnetic response was analyzed by the temperature evolution of the magnetic permeability from room temperature to 780 C. It was found that the high-temperature soft magnetic behavior is improved with increasing Co content for x <= 0.5, which is ascribed to reinforcing magnetic coupling between the crystals, however, a decrease of mu(i) was observed for the Co richest sample. The observed mu(i) behavior as a function of Co content is interpreted in terms of variations in the degree of exchange coupling. (C) 2008 Elsevier B.V. All rights reserved.